Abstract: The present invention discloses an architecture for a concurrent dual-band high-frequency receiver. The invention combines a concurrent dual-band front-end subsystem having a dual-band antenna, dual-band pre-amplifier filter and concurrent dual-band LNA with a novel image rejection downconverter to provide the functions of a typical receiver, including reception, amplification and downconversion of a signal in two discrete desired frequency bands simultaneously.

Abstract: A single conversion frequency converter comprises an image reject mixer and a local oscillator. The local oscillator comprises a variable frequency oscillator and a variable divider. The variable divider supplies to the mixer a local oscillator signal whose frequency is a sub-multiple of the frequency of the variable frequency oscillator.

Abstract: A feedback image rejection downconversion system is described, which can be used in low IF receivers with good performance and completely integrated. In the forward path of the system, quadrature mixers and complex filters are used for frequency downconversion and separation of the RF signal from the image signal. In the feedback path, a correlator, a gain mismatch estimator and two VGAs have been used to detect, estimate and compensate the amplitude and phase mismatch between the forward I and Q path signals. The whole system is self-tuned and can operate in both closed and open loop mode. A very high and robust image rejection ratio (over 60 dB) has been achieved.

Abstract: A superhet receiver in which an input signal is frequency down-converted in a first mixer (14) to produce a first IF signal comprising a wanted channel signal and an image channel signal. The first IF signal, without image rejection filtering, is frequency down-converted in a second mixer (24) to produce a second, lower IF signal comprising at least the wanted channel signal having a bandwidth corresponding to a predetermined passband of a channel filter (32) coupled to the output of the second mixer. The local oscillator signals used in the first and second frequency down conversion processes are varied in order to produce successively different image channel signals in the first IF signal and to maintain the wanted channel signal in the second IF signal within the passband of the channel filter (32).

Abstract: Disclosed are a low pass filter, and a direct conversion receiver (DCR) implementing the same, which filter and second signal channels with improved phase and gain match, allowing use of the filter and DCR in wideband environments. A first M-pole filter channel, comprised of a first plurality of 2-pole active filter stages, filters the first signal channel. A second M-pole filter channel, comprised of a second plurality of 2-pole active filter stages, filters the second signal channel. One of the second plurality of 2-pole filter stages includes two variable components. The values of the variable components of the second M-pole filter channel are adjusted to match the gain and phase of the first and second filter channels.

Abstract: A semiconductor integrated circuit device includes a first phase shifter configured to make a phase difference of 90 degrees between local signals, first and second mixer circuits configured to mix the local signals with a received signal, a second phase shifter configured to make a phase difference of 90 degrees between output signals of the first and second mixer circuits to output first and second output signals, an adder configured to add the first and second output signals, a subtracter configured to subtract the first and second output signals, a signal intensity detector configured to compare between an intensity of an output signal of the subtracter with a reference level intensity, and a power supply control circuit configured to disable either of the first and second mixer circuits or either of the first and second mixer circuits and the first phase shifter according to a comparison result.

Abstract: An image trap filter disposed between the low noise amplifier and the mixer of a radio frequency receiver that overcomes the adverse effect of process variations on image signal rejection for both a single-band radio frequency receiver and a multi-band radio frequency receiver by setting the image trap filter response at the center of the band of interest at production test. The image signal problem is presented at the input of the radio frequency receiver and the image trap filter is adjusted for the desired frequency response.

Abstract: A method and apparatus that provide a frequency conversion in a radio frequency front-end are disclosed, including a frequency divider that divides an input signal frequency by a predetermined value to produce an output signal frequency; and a frequency mixer that mixes the output signal frequency with a carrier signal frequency to produce a converted signal frequency, which is substantially equal to a difference between the output signal frequency and the carrier signal frequency. The predetermined value and the input signal frequency are selected such that the carrier signal frequency is not substantially equivalent to an integer multiple of the output signal frequency. The method and apparatus can be used in a wireless communication receiver including wireless communication systems and wireless LAN systems.

Abstract: A mixer architecture receives an input signal, which is frequency translated from a first frequency to a second frequency in a first mixer; the resulting output signal is retranslated back to the first frequency in a second mixer, the retranslated signal is added to a sample of the input, with gain and phase control, and the resulting error signal is added to the input signal when it is applied to the first mixer. This linearises the mixer output by compensating for any distortion introduced in the forward path. The mixer architecture is applicable for use in receivers or transmitters.

Abstract: A notch filter with a high Q factor, which is integrated with a first and a second cascoded LNA, is totally contained on an integrated chip. The notch filter, comprising two Q-enhancement circuits, is coupled to the second differential LNA. The two Q-enhancement circuits are combined to generate sufficient negative impedance to compensate for the loss in the on-chip low Q inductors. To improve the image rejection of the notch filter in a wide frequency band, the notch filter uses an automatic current tuning circuit which consists of an analog multiplier and fixed and voltage controlled current sources. Furthermore, by modifying the connection and location of the tunable varactor, another wideband tunable notch filter is implemented. The notch filter can be applied in all current wireless receiver systems.

Abstract: A mixer circuit with image frequency rejection comprising a quadrature phase divider (30, 30′) presenting an input connected to the input (Fi) of the mixer circuit and two outputs respectively delivering two signals in phase quadrature which are applied respectively to two simple mixers (31, 32; 31′, 32′), said mixer circuit comprising a quadrature phase and frequency divider (33, 33′) having a frequency division ratio and presenting two inputs respectively connected to the respective outputs of the two simple mixers (31, 32; 31′, 32′) and a first output delivering a first output signal (Fo) of the mixer circuit, which signal is applied to the inputs of the two simple mixers.

Abstract: An entire radio transceiver can be completely integrated into one IC chip. In order to integrate the IF filters on the chip, a heterodyne architecture with a low IF is used. A single, directly modulated VCO is used for both up-conversion during transmission, and down-conversion during reception. Bond-wires are used as resonators in the oscillator tank for the VCO. A TDD scheme is used in the air interface to eliminate cross-talk or leakage. A Gaussian-shaped binary FSK modulation scheme is used to provide a number of other implementation advantages.

Abstract: A compensation circuit to correct for mismatch in a quadrature receiver comprises first and second mixers to receive a radio frequency (RF) modulated signal. One mixer receives an I local oscillator signal while the second mixer receives a Q local oscillator signal wherein the I and Q local oscillators have frequencies that are substantially identical. The output of the first and second mixers are coupled to first and second filters, respectively, which generate the I and Q output signals, respectively. Inherent circuit mismatch generate gain and/or phase errors that result in mismatch in the I and Q output signals. A correction circuit automatically applies a correction factor to at least one of the I and Q output signals to correct the gain and/or phase error by applying a multiplication factor to at least one of the I and Q output signals to thereby generate a corrected signal. The correction factors must be determined on a unit by unit basis.

Abstract: A communications receiver architecture characterized by a relatively low intermediate frequency (IF) and a polyphase filter. The receiver includes an input amplifier coupled to a carrier signal. Respective I and Q demodulators are coupled to the output of the input amplifier. A quadrature local oscillator (LO) generator provides respective LO_I and LO_Q inputs to the I demodulator and LO_Q inputs to the I demodulator and to the Q demodulator. The quadrature LO generator is driven by a phase-locked LO, and the LO frequency is such that an IF of, in one embodiment, approximately 1 MHz results. The I demodulator and Q demodulator outputs are applied through respective A/D converters to a polyphase filter. The polyphase filter outputs are then processed by a digital I/Q demodulator.

Abstract: Radio receivers are known in the art. A conventional receiver requires external components for RF/image selectivity, IF selectivity and demodulation. Other solutions are, for example, a number of correction algorithms, which is an expensive solution. Instead, the “weak” image point is positioned at the side of the desired channel with the lowest unwanted RF signal strength. While this does not necessarily increase the actual image rejection, the perceived image rejection is clearly improved.

Abstract: Because there are different voltages at two current output terminals of a current divider, the voltages at the current input terminals of two current switch circuits are not affected mutually even with a large amplitude of local signals. Accordingly, the performance of a quadrature mixer can be enhanced by increasing the amplitude of the local signals. Bias currents are supplied to the two current switch circuits through the current divider from a common DC current source which essentially supplies a bias current to a V/I converter and, therefore, power consumption is reduced.

Abstract: The present invention provides a mixer circuit which can suppress image interfering signals and interfering signals related to higher harmonic component of an oscillator. Using the mixer circuit, it is possible to provide a high-frequency signal receiver which maintains good signal receiving condition. This mixer circuit comprises a plurality of mixers, oscillators, a plurality of oscillator phase shifters which serve to phase-shift the output of the oscillators and supply the output to the mixers, and a plurality of intermediate frequency phase shifters which serve to phase-shift the output of the mixers. The high-frequency signal receiver comprises at least a pre-filter and the mixer circuit.

Abstract: A signal receiver and a method for separating a RDS signal component from a received signal is described. After the received signal has been downconverted to the baseband, the baseband signal is split up into a first baseband signal for a first signal path and a second baseband signal for a second signal path. The first baseband signal is highpass filtered and forwarded to a frequency synchronization unit that generates a frequency synchronization carrier. The second baseband signal is modified in accordance with the frequency synchronization carrier provided by the first signal path, and a synchronized baseband signal is obtained that still comprises the full range of the RDS signal's spectral components.

Abstract: A satellite broadcast reception converter, having a simple structure, capable of reducing an output return loss even if a circuit board is relatively smaller than a chassis is provided.

Abstract: An apparatus and method for radio signal parallel processing are provided, wherein the apparatus, which receives and processes in parallel a first and second carrier signal of frequencies &ohgr;1 and &ohgr;2 (&ohgr;2>&ohgr;1), includes: a first local oscillator which outputs a signal of frequency &ohgr; to a first frequency mixer which converts the first carrier signal into a signal of a first intermediate frequency (&ohgr;−&ohgr;1) and a signal of another first intermediate frequency (&ohgr;+&ohgr;1), and outputs the converted signals; and a second frequency mixer which converts the second carrier signal into a signal of a first intermediate frequency (&ohgr;2−&ohgr;) and a signal of another first intermediate frequency (&ohgr;2+&ohgr;), and outputs the converted signals. With the above, the capacity of data reception and transmission increases, the complexity of implementing the apparatus is low, and the cost of manufacturing the apparatus is reduced.

Abstract: The present invention relates to a process and a system for reducing leakage of LO to the RF-port (LLO) in a real system that converts the frequency of a first signal, i.e. the LO signal, by mixing the first signal with a second supplied signal SI to a third signal SO of a frequency that is different from the frequency of the first and second signal. More specifically the invention relates to a process and a system that are applied to suppress LLO in real image reject balanced passive mode transistor mixers. Further, the invention also relates to a balanced passive mode transistor mixer and an image reject balanced mixer to be used in said process and system.

Abstract: A novel RF to IF converter operates in two modes allowing both wide bandwidth signals and narrow bandwidth signals to be processed using the same wide bandwidth bandpass filter as well as a dual-mode image-reject mixer. As a mobile receiver, both wide bandwidth WCDMA or IMT-2000 signals and narrow bandwidth GSM signals pass through the same wide bandwidth channel select filter. In the GSM mode, signals lying to one side of the frequency range of the narrow GSM signal are attenuated by the wide bandwidth channel select filter. Then signals lying to the other side of the GSM signal are attenuated by an image-reject mixer. The image-reject mixer also downconverts the GSM signal. In the WCDMA or IMT-2000 mode, the wide bandwidth channel select filter attenuates signals outside of the WCDMA or IMT-2000 channel bandwidth, and the image-reject mixer downconverts the wide bandwidth signal without rejecting signals.

Abstract: In a system and method for simultaneously receiving or switching between dual frequency carrier signals in a GPS receiver, the GPS receiver is adapted to utilize different harmonics of a sub-harmonic frequency generator, which may include a lower frequency voltage controlled oscillator (VCO) to detect the L1 and L2 GPS carriers. A sub-harmonic mixer may be used to simultaneously down convert the L1 and L2 signals to a lower intermediate frequency (IF). A second mixer may be an image reject (IR) mixer used to separate the downconverted L1 and L2 signals. This mixer may be configured to simultaneously monitor the L1 and L2 signals, or to switch between the L1 and L2 signals. High frequency switching is not required of the radio frequency (RF) input or local oscillator signals, and simultaneous L1 and L2 reception is enabled without a 3dB image noise degradation.

Abstract: An image trap filter used in a radio frequency receiver for filtering an image signal from a radio frequency signal. The image trap filter includes an inductor and a capacitor connected in series in a first branch with the first branch connected in parallel with an impedance in a second branch. For low-side injection of the local oscillator signal (i.e., the frequency of the local oscillator signal is lower than the radio frequency signal), the impedance in the second branch is a capacitor and the series-connected inductor and capacitor in the first branch resonate at the frequency of the image signal and present a low impedance at the frequency of the image signal and a somewhat higher inductive impedance at the frequency of the radio frequency signal that resonates with the capacitor in the second branch at the frequency of the radio signal. For high-side injection of the local oscillator signal (i.e.

Abstract: It is described an image rejection, sub-harmonic frequency converter, realized in microstrip, particularly adapted to be used in mobile communication equipment, The converter avails of two identical sub-harmonic mixers employing each one or two pairs of diodes in antiparallel, obtained on a same silica substrate, and of a structure of hybrids performing appropriate phase combination adapted to suppress the image band in the converted signal. The mixers include filtering structures preferably consisting, but no limited to the same, of stubs &lgr;/4 long, at the local oscillator frequency, having a free end, in short or open circuit, respectively. According to an alternative embodiment, said stubs are replaced by appropriate filters implemented with concentrated structures (L and C) performing the same transfer function of the stubs in microstrip.

Abstract: A receiver system (10) includes a first stage of modulation (46, 51) which modulates a radio-frequency input signal (17), and a second stage of modulation (56, 61, 66, 71) which modulates outputs from the first stage. Combining circuits (76, 77) combine selected outputs of the second stage to produce two outputs (18, 19) from the receiver system. The first stage receives modulating signals (22, 23) from a first oscillator (21), and the second stage receives modulating signals (27, 28, 32, 33) from second and third oscillators (26, 31). The second and third oscillators each operate at a substantially lower frequency than the first oscillator. The phase difference between the modulating signals produced by each of the second and third oscillators is adjusted so that there is minimum image power in each of the system outputs (18, 19), even if the modulating signals from the first oscillator are not in phase quadrature.

Abstract: The remotable, ultrawide band optical image rejection downconverter uses sub-carrier modulation techniques without concern for image frequency interferences in the shifted signal, thereby allowing telecommunications systems to downconvert densely multiplexed communications channels into a low frequency band where conventional electronics can perform signal-processing functions. This invention has the image rejection (>120 dB) to provide unambiguous signals for direction finding applications and exhibits an efficient image that permits multi-octave microwave frequency reception and compression. This invention is intrinsically remoteable, and due to the various optical and electrical components proves to be very useful and practical in numerous fiber optic and antenna systems.

Abstract: An image reject sub-harmonic mixer that employs less components than known image reject mixers. The mixer includes a 90° RF coupler, two high pass filters, two anti-parallel diode pairs, two low pass filters and a 90° IF coupler. RF and LO signals are applied to isolated input ports of the 90° coupler. In-phase and quadrature-phase copies of the RF and LO signals are provided at output ports of the coupler. The diode pairs mix the RF and LO signals to generate first and second intermediate frequency signals that are separated in-phase. The high pass filters reject the IF signals to prevent IF power from coupling to the RF and LO ports of the coupler. The low pass filters pass the IF signal and reject the LO and RF signals. Image rejection is obtained by combining the IF outputs of the two diode pair in the 90° IF hybrid.

Abstract: A radio FM receiver is provided with a receiver portion with quadrature channels for converting received radio frequency signals into center frequency quadrature signals, a center frequency filter circuit connected to the former for suppressing undesirable image frequencies, and a first quadrature PLL demodulator for demodulating the obtained center frequency quadrature signals, said PLL being tuned to the carrier frequency within the selected frequency band. An error detector is furthermore present for detecting amplitude and phase errors in the quadrature channels, which error detector in response to the quadrature components of the center frequency signals, the quadrature signals of a VCO in the quadrature PLL demodulator, and the filtered difference said quadrature components of the center frequency signal, supplies amplitude and phase correction signals to a quadrature channel correction network which is provided between the filter circuit and the quadrature PLL demodulator.

Abstract: A system and method for a single conversion tuner which generally uses phase shifted in-phase and quadrature-phase signal paths as an image rejection circuit. Through the use of broadband input LNA and mixer circuits, substantially the entire input signal bandwidth may be processed in the tuner. The broadband input LNA may pass the signal through to the mixers, which may split the signal into in-phase and quadrature terms. Then the in-phase term may be shifted by plus 45 degrees and the quadrature may be shifted by minus 45 degrees. When the terms are subsequently summed together, the desired signal components add together, while the undesired image components subtract from each other. In this way the image signal is suppressed, thus generally eliminating the need for a notch filter. A phase error correction feedback loop may be implemented to compensate for errors between the separate circuit paths.

Abstract: A single conversion tuner is provided for receiving digital terrestrial broadcast signals. The tuner comprises a single frequency changer comprising a mixer and local oscillator controlled by a PLL synthesiser. A non-alignable variable low pass filter is provided between the tuner input and the mixer, which is of the image reject type. The bandwidth of the filter is varied so as to track the local oscillator frequency to provide sufficient attenuation of the image channel without requiring any alignment during manufacture.

Abstract: A method and system is described for several embodiments of a communication system. In a first embodiment, a method and system is described wherein a signal is received and down-converted and wherein power consumption can be characterized as “ultra-low.” In a second embodiment, a method and system is described wherein undesirable images are rejected in a down-conversion system. In a third embodiment, a method and system is described wherein a signal is transmitted in a highly efficient manner. In one implementation the present invention is used in a family radio system.

Abstract: A controller area network transceiver and a transmission method for a controller area network provides improved symmetry between its differential output signal CANH and CANL such that capacitive imbalance is minimized. The transceiver disclosed herein includes a driver including a non-inverted output that couples to the first output terminal CANH and a inverted output that couples to the second output terminal CANL. A receiver comparator includes a non-inverted input coupled to the first output terminal CANH and a inverted input coupled to the second output terminal CANL. A first and second impedance matching circuit portions capacitively balance the first and second output terminals such that efficient common-mode rejection is enabled by setting the RC time constants formed by each impedance matching circuit and external resistances to be substantially equivalent.

Abstract: Adaptive image rejection in a wireless communication receiver is implemented using a dual conversion technique where a first mixer is used to downconvert the received RF signal to a first IF. A second mixer is used to downconvert the first IF to a baseband signal. A Local Oscillator (LO) drives the first mixer. The baseband signal is filtered and data is extracted. A bit error rate is determined from the extracted data. If the bit error rate falls below a predetermined threshold, a controller adjusts the frequency of the LO. If the LO was previously configured as a low side LO the controller adjusts the frequency of the LO to a high side LO frequency. Conversely, if the LO is configured as a high side LO the controller adjusts the frequency of the LO to be the low side LO frequency.

Abstract: An image reject mixer for a low power battery operated radio telephone application. First and second doubly balance mixer circuits are connected to receive a differential radio frequency signal. Each of the doubly balance mixer circuits receives a local oscillator signal and a complimentary quadrature local oscillator signal. A first and second differential current produced by the first and second doubly balance mixture are combined in a quadrature combining circuit. The quadrature combining circuit adds an additional 90° of phase shift between the pairs of signals produced by each doubly balance mixture, so that the mixture output signals are added in a phase quadrature relationship thereby canceling unwanted spur and image components contained in the respective mixer output circuits.

Abstract: A heterodyne receiver includes a tuner to select a frequency of a received signal and a converter to change the frequency of the received signal to an intermediate frequency. A single-pole/double throw switch has an input coupled to an output of the converter, a first output connected to a first band-pass filter and a second output connected to an amplifier. A second band-pass filter is coupled to an output of the amplifier, and a demodulator is coupled to an output of the second band-pass filter to produce an output signal and a characteristics signal. A logic circuit is coupled to receive the characteristics signal and for by-passing the first band-pass filter if the characteristics signal is less than a predetermined threshold.

Abstract: With the rising popularity in wireless personal communication systems (PCS), there is a need for low-power, low-cost radio receivers. Low cost can be achieved by integrating the required functions as much as possible, thus minimizing the number of off-chip components. The present invention discloses a novel topology for integrating an image reject filter with a traditional low-noise amplifier (LNA) for use in the front-end of a superheterodyne receiver. Previous topologies employing additional filter stages after the LNA have suffered from poor performance and excessive current consumption. Advantageously, the topology of the present invention requires minimal additional circuitry to perform the filtering function, uses only minimal additional current and does not suffer from the same performance limitations as previous topologies.

Abstract: In a system and method for simultaneously receiving or switching between dual frequency carrier signals in a GPS receiver is adapted to utilize different harmonics of a sub-harmonic frequency generator, which may include a lower frequency voltage controlled oscillator (VCO) to detect the L1 and L2 GPS carriers. A sub-harmonic mixer may be used to simultaneously down convert the L1 and L2 signals to a lower intermediate frequency (IF). A second mixer may be an image reject (IR) mixer used to separate the downconverted second L2 signals. This mixer may be configured to simultaneously monitor the L1 and L2 signals, or to switch between the L1 and L2 signals. High frequency switching is not required of the radio frequency (RF) input or local oscillator signals, and simultaneous L1 and L2 reception is enabled without a 3 dB image noise degradation. This method minimizes the RF components and power dissipation in a dual frequency GPS receiver, while optimizing the functionality and performance.

Abstract: Methods and apparatus are provided for image rejection correction in a radio frequency (RF) receiver (100). The RF receiver (100) receives an RF input signal and converts the RF input signal to an input signal at another frequency. A tone signal is generated at an image frequency. The tone signal is mixed with an RF tuning signal to provide an image signal. The image signal is corrected using an image correction network (202) having first and second coefficients to provide a corrected signal. A wanted energy level of the corrected signal is determined. Best values of the first and second coefficients are determined in response to the wanted energy level of the filtered signal. The input signal is corrected using the best values in the image correction network (202).

Abstract: An image-rejecting antenna apparatus includes an antenna unit for receiving or transmitting a wireless signal and an image-reject unit for removing an image component signal having a predetermined frequency from among signals received from the antenna unit. In an image-rejecting antenna apparatus that receives a predetermined signal and provides a processed signal to a RF circuit unit for performing a predetermined function may also include an impedance matching unit for matching an impedance of the antenna unit with an impedance of the RF circuit unit and for providing the signal from which the image component signal has been removed to the RF circuit unit. A noise component of an image frequency that is transmitted to a subsequent circuit can be minimized or removed by including an image-reject unit when designing an antenna and a matching circuit, thereby improving the image-rejecting capabilities of an entire receiver.

Abstract: In a superheterodyne receiver, energy can bypass a filter by magnetically coupling to a metallic radio frequency shield. This is especially a problem with small form factor devices in which the metallic radio frequency shield is positioned close to the filter. By using a ferrite-embedded element positioned between the filter and the RF shield, some of the undesired harmonics produced by the mixer can be dissipated into heat.

Abstract: An oscillator has a resonator which includes at least one capacitor and at least one inductor. The resonator supplies a first signal of a first frequency at an output of the resonator. A frequency multiplier or a frequency divider is connected, via an input thereof, to the resonator output. The frequency multiplier or frequency divider supplies a second signal of a second frequency at an output of the frequency multiplier or frequency divider. The second frequency is n times or 1/n times (n≧2 and integer) the first frequency. A tuned circuit is part of the resonator and forms a short circuit or an open connection for the second frequency.

Abstract: A system and method for effecting wideband image rejection. In a receiver implementation, the inventive method includes the steps of receiving a first signal in a first frequency band and generating in-phase and quadrature signals therefrom. The phase of the in-phase signal is shifted to provide a second signal and the phase of the quadrature signal is shifted to provide a third signal. A predetermined phase relationship is thereby effected between the second and the third signals. The second and third signals are then summed to provide an output signal which has minimal interference from a mixing signal. In an illustrative receiver application, the phase shifting is achieved via the use of all pass networks. Each of the all pass networks include a differential amplifier having first and second input terminals. The first and the second terminals are connected to a first end of first and second resistive elements, respectively.

Abstract: An RF tuner and tuning method employs analog quadrature mixing with a coarse-stepwise tunable local oscillator to a near-baseband passband region, followed by A/D conversion of the I and Q signals, correction of phase, group delay, and amplitude errors, image rejection, and translation to baseband by (1) fixed frequency translation, (2) stepwise channelized translation, or (3) essentially continuously variable tuning over a given digital tuning range. The near-baseband passband region is sized and located such that alternating image rejection provides non-redundant and complete tuning coverage of a desired high frequency spectrum with a local oscillator step size equal to about twice the digital tuning range or about twice the number of channels digitally stepwise tunable times the channel width, effectively doubling the typical local oscillator step size.

Abstract: In a communications receiver for quadrature demodulation, a feedback technique for reducing the image response of the receiver. The communications receiver includes an I demodulator and a Q demodulator. A local oscillator (LO) signal is provided by a PLL to a quadrature LO generator that provides an LO_I signal to an I demodulator and an LO_Q signal to a Q demodulator. The LO_I and LO_Q signals are amplitude and phase-controlled versions of the LO signal. An image/signal ratio (I/S) detector detects the relative phase difference and the relative amplitude difference between the respective output terminals of the I demodulator and the Q demodulator and applies an amplitude control signal and a phase control signal to corresponding amplitude control and phase control inputs of the quadrature LO generator. The I/S detector calibrates the quadrature LO generator during the interstitial interval between the reception of data packets.

Abstract: Methods, systems, and apparatuses for down-converting an electromagnetic (EM) signal by aliasing the EM signal, and applications thereof are described herein. Reducing or eliminating DC offset voltages and re-radiation generated when down-converting an electromagnetic (EM) signal is also described herein. Down-converting a signal and improving receiver dynamic range is also described herein.

Abstract: An integrated receiver with channel selection and image rejection substantially implemented on a single CMOS integrated circuit is described. A receiver front end provides programable attenuation and a programable gain low noise amplifier. Frequency conversion circuitry advantageously uses LC filters integrated onto the substrate in conjunction with image reject mixers to provide sufficient image frequency rejection. Filter tuning and inductor Q compensation over temperature are performed on chip. The filters utilize multi track spiral inductors. The filters are tuned using local oscillators to tune a substitute filter, and frequency scaling during filter component values to those of the filter being tuned. In conjunction with filtering, frequency planning provides additional image rejection. The advantageous choice of local oscillator signal generation methods on chip is by PLL out of band local oscillation and by direct synthesis for in band local oscillator.

Abstract: Disclosed are systems and methods which utilize an image reject mixer in an out-of-band mixer application such as in a forward data channel frequency converter. For example, according to a preferred embodiment, an image reject mixer is utilized to provide a relatively high degree of image rejection with respect to an out-of-band signal, thereby relaxing the requirement for filtering in the signal path leading to the mixer circuitry. Preferred embodiments of the invention are substantially or fully implemented utilizing integrated circuit technology.

Abstract: Wireless communications equipment that wirelessly communicates signals on a plurality of communication frequencies includes: a baseband frequency-side frequency conversion means that performs conversion between baseband signals on the baseband frequency and signals on a stipulated frequency higher than the baseband frequency and different from the intermediate frequency, an intermediate frequency-side frequency conversion means that performs conversion between the signals on said stipulated frequency and intermediate frequency signals on a plurality of intermediate frequencies corresponding to a plurality of communication frequencies, and an unwanted frequency signal component removal means that removes signal components of unwanted frequencies from the signals on said stipulated frequency.

Abstract: A compensation circuit to correct for mismatch in a quadrature receiver comprises first and second mixers to receive a radio frequency (RF) modulated signal. One mixer receives an I local oscillator signal while the second mixer receives a Q local oscillator signal wherein the I and Q local oscillators have frequencies that are substantially identical. The output of the first and second mixers are coupled to first and second filters, respectively, which generate the I and Q output signals, respectively. Inherent circuit mismatch generate gain and/or phase errors that result in mismatch in the I and Q output signals. A correction circuit automatically applies a correction factor to at least one of the I and Q output signals to correct the gain and/or phase error by applying a multiplication factor to at least one of the I and Q output signals to thereby generate a corrected signal. The correction factors must be determined on a unit by unit basis.